Our objective is to revolutionize high performance liquid chromatography using new principles and a new analytical system which allows multiple-parallel analysis of many samples with high resolution, automatic data acquisition, and data analysis and display. The high pressures required for high resolution are obtained by centrifugal force, which also moves samples from a transfer disc to the chromatographic columns. A gradient segmentation device cuts one elution stream into small fractions which are introduced equally into all columns. An eluting density gradient, when combined with centrifugal force, maintains the sample zone, and all separated zones in position, and perpendicular to a radius through the column. The density gradient also keeps tight zones as they move through the flow cell. Two stream segmentation devices are provided to allow, in concert with suitable valving, flow in either inboard or outboard direction through the column. Outboard elution with the flow cell centripetal to the column is used with gradients of decreasing density, while elution in an inboard direction is used with gradients of increasing density. Since the system has no pumps, runs many columns in parallel, and uses one optical system and microprocessor for data acquisition and analysis, and provides analyses at a high rate, we believe that this system will, when perfected, supplant a large fraction of the HPLC systems in present use.